Ophthalmic lens



Feb. 18, 1941. H. w. HILL ErAL- I OPHTHALMIC LENS Filed April 7, 1938 Patented Feb; 18, 1941 UNITED STATES PATENT OFFICE OPHTHALMIC LENS Harry Wi Hill and Edgar D. Tillyer, Southbridge, Mass, assignors to American Optical Company, Southbridge, Mass, a voluntary association of Massachusetts Application April 7, 1938, Serial No. 200,702

1 Claim. (CI. 88-54) This invention relates to improvements in necessary to give the desired correction in the multifocal and bifocal lenses. near vision portion.

One of the principal objects of the invention It will be apparent that by forming the deis to provide a unitary multifocal lens having sired curvatures on the portions and 6, and 5 any desired prescriptive power in any one of its 3 and 4, it will be possible to obtain any desired 5 optical fields, and particularly to have any deprism and cylinder powers in either the distance sired prism or cylindrical power in any one of portion l or the near vision portion 2, or differits fields and to provide an improved, inexpensive ent corrections in each of the fields. As stated .and efficient process for producing the same. above, this type of correction has been highly Other objects and advantages of the invendesired, but due to the lack of any known proction will become apparent from the following ess or method of making such a lens, it has not description taken in connection with the accombeen previously possible to obtain these results. panying drawing. It will be apparent that many In the manufacture ofthe lens embodying'the changes may be made in the details of coninvention, we first take a blank 1, as shown in I struction and steps of the processes within the Fig. II, and by the methods previously known in scope of the accompanying claim. I, therefore, e art grinding p e bifocal es, e do not wish to be limited to the exact details grind and Polish the inner Surface 5 0f the reedshown and described, as the preferred form only ing vision portion to the necessary curvature to 00 has been shown by way of illustration. give the desired surface power to this portion. Referring to the drawing: We then grind the necessary powers on the Fig. I is a front view of a lens blank embodysurfaces 3 and 4 of the distance portion 2 to ing the invention; give the desired correction through this portion Fig. II is a sectional view taken on line II-II and through the reading vision portion. 05 of Fig. I; and It will be understood that by grinding the Fig. III is a view similar to Fig, II but of a reading vision portion 2 with apparatus which finished lens embodying the invention, has been used in the art in the past for grind- In the present day multifocal and bifocal readi Si Portions Onepieee hifOeeJS lenses, made of one piece of material, it has been With Other then found Segments, t reading 0 found inexpedient and almost impossible to obvision po 2 of practically a y es 011ttain prism and cylinder corrections in either line or contour may be obtained. the reading or distance vision fields, and par- It Will e readily pp at W h th form ticularly when such correction is desired in the of l n any desired prism 0 y n corr tion reading field only. It is, therefore, a principal y he Obtained i the distance Vision Portion object of the invention to provide a form of r in the reading vision p r or h, a

" multifocal lens that will lend itself to the prodifferent Cylindrical correction or prismatic-cor-' S vision of these corrections in either field or all rection ay be ta in either portion f fields as desired to thus supply a deficiency now that Of the Otherexisting in the art. It will be noted that the reading vision por- Referring more particularly to the drawing tion depression 6 may be formed on either the wherein similar reference characters designate front Surface 3 or the rear Surface 4 of the lens 40 corresponding parts throughout, we have shown blank as desired in Fig. I a lens blank embodying the invention. 3 i g are examples of the liens This lens is made of a single homogenous piece em odymg the mventmn and by means of Whlch of glass and comprises the distance portion I i gg g gg qg g zf g fifig gfgg i sphere and the a Vlslon 9 readmg portlon in the distance portion and a reading vision por- The portion I has itsfront surface 3 and its tion f a +330 diopter ith e, cylinder is rear surface 4 of any desired curvature necessary desired. we would fi t grind on the urfa 5 to give the desired power to the finished lens. 4'00 aiopter curve We would t grind t 50 While the lens has been Shown as Curved surface 4 with a 6.00 diopter curve in one me- 60 Spherical, it y be flat non-Curved, torie, ridian and a 6.50 diopter curve in the other cylindrical, aspherical, or any desired curvature, meridian, Then, using the same axis, we would or it may be prismatic. grind on the front surface 3 a +7.00 diopter The portion 2 may have its front surface 5 curve in one meridian and a +7.50 diopter curve and its rear surface 6 of any desired curvature in the opposite meridian. The resultant lens 55 would then be a +1.00 diopter for the distance portion and the reading total would be a +3.00 diopter power with a +.50 diopter cylinder power in the reading portion only.

If it is desired to make a lens with 2. +1.00 diopter power in the distance vision portion with a +2.00 diopter addition in the reading portion and a 1 degree prism in the reading portion only, we would first grind a 4.00 diopter curve on the surface 6.

We would then grind and polish the surface 4 with a 6.00 diopter curve and then grind and polish on the front surface of the blank a +7.00 diopter curve with a 1 degree prism having its base in the desired direction. The resultant lens would have a +1.00 diopter power in the distance vision portion and a +3.00 diopter power on the reading vision portion with a 1 degree prism on the reading vision portion only with its base in the desired direction.

I If it is desired to have different cylinder axis and cylinder powers in the reading and distant fields all that is necessary is to grind the required front curve which, in combination with the reading portion, gives the near prescription, then place on the side that the reading portion is on, a sphero cylinder with the power and at the axis necessary to obtain the correct distance portion computed by the ordinary method of combining oblique sphero cylinder surfaces.

From the above, it will be seen that we have provided simple, eficient and economical means for obtaining all the objects and advantages of the invention, and have provided both a new and improved article for manufacture and a new and improved process for producing the same.

Having described our invention, we claim:

A multifocal ophthalmic lens having a distance vision field and a near vision field, said lens comprising a single piece of lens medium having a depressed area on one side thereof with a spherical bottom surface of finished optical quality entirely surrounded by a cliff like wall with said bottom surface being of a curvature controlled so as to introduce in part the optical characteristics desired in the near vision field and yet be cupped by an amount which will enable the portion of the lens producing the major field to be reduced during the forming of finished optical surfaces on the opposed sides thereof to a usable minimum thickness without grinding into the curve in the bottom of said depressed area, a finished optical sphero-cylindrical surface on the side of the lens opposite the depressed area of a curvature so controlled that when combined with the spherical curvature of the bottom of the depressed area it will introduce a desired sphero-cylindrical power in the near vision field of the lens, said sphero-cylindrical surface being formed to such a depth as to reduce the thickness of the near vision field to a minimum usable thickness and so as to allow an optical surface to be formed on the opposite side of the lens to a depth sufiicient to reduce the thickness of the distance vision portion of the lens and the cliff like wall surrounding the near vision field to a desired minimum thickness without grinding into the surface in the bottom of the depressed area and an optical surface of any of the known type in the art on the side of the distance vision portion of the lens having the depressed area therein of such a curvature as to control the resultant focal power of the distance focal field of the lens independently of the power of the near vision field, the thickness of the cliif like wall surrounding the near vision field being initially of a thickness sufficient to permit any of said known optical surfaces to be formed on said side of the lens and said optical surface being formed to such a depth as to reduce the major portion of the lens to a desired minimum thickness and, because of the controlled cupping curvature of the spherical bottom surface of the depressed area, not grind into said surface.

HARRY W. HILL. EDGAR D. TILLYER. 

